title: Non-regulatory CD8+CD45RO+CD25+ T-lymphocytes may compensate for the loss of antigen-inexperienced CD8+CD45RA+ T-cells in old age.
abstract: The age-related decline in immune system functions is responsible for the increased prevalence of infectious diseases and the low efficacy of vaccination in elderly individuals. In particular, the number of peripheral naive T-cells declines throughout life and they exhibit severe functional defects at advanced age. However, we have recently identified a non-regulatory CD8+CD45RO+ CD25+ T-cell subset that occurs in a subgroup of healthy elderly individuals, who still exhibit an intact humoral immune response following influenza vaccination. Here, we demonstrate that CD8+CD45RO+CD25+ T-cells share phenotypic and functional characteristics with naive CD8+CD45RA+CD28+ T-cells from young individuals, despite their expression of CD45RO. CD8+CD45RO+ CD25+ T-cells also have long telomeres and upon antigenic challenge, they efficiently expand in vitro and differentiate into functional effector cells. The expanded population also maintains a diverse T-cell receptor repertoire. In conclusion, CD8+CD45RO+CD25+ T-cells from elderly individuals compensate for the loss of functional naive T-cells and may therefore be used as a marker of immunological competence in old age.
authors.affiliation: Institute for Biomedical Aging Research, Austrian Academy of Sciences, A-6020 Innsbruck, Austria. dietmar.herndler-brandstetter@oeaw.ac.at
authors.forename: Dietmar
authors.initials: D
authors.lastname: Herndler-Brandstetter
authors.forename: Ellen
authors.initials: E
authors.lastname: Veel
authors.forename: Gerhard T
authors.initials: GT
authors.lastname: Laschober
authors.forename: Gerald
authors.initials: G
authors.lastname: Pfister
authors.forename: Stefan
authors.initials: S
authors.lastname: Brunner
authors.forename: Susanne
authors.initials: S
authors.lastname: Walcher
authors.forename: Walther
authors.initials: W
authors.lastname: Parson
authors.forename: Günter
authors.initials: G
authors.lastname: Lepperdinger
authors.forename: Beatrix
authors.initials: B
authors.lastname: Grubeck-Loebenstein
mesh_terms: D000328:Adult; D000368:Aged / Q000502:physiology*; D000375:Aging / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D002469:Cell Separation; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology / Q000502:physiology; D019672:Genes, T-Cell Receptor / Q000276:immunology; D006801:Humans; D017403:In Situ Hybridization; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology*; D017493:Leukocyte Common Antigens / Q000276:immunology*; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013268:Stimulation, Chemical; D016615:Telomere / Q000648:ultrastructure
chemical_list: D018076:DNA, Complementary; D053645:Interleukin-2 Receptor alpha Subunit; D017493:Leukocyte Common Antigens